Method of producing dry metal sulfonates of improved oil solubility



Patented Nov. 26,1946

UNITE STES PATENT GFFICE METHOD OF PRODUCING DRY METAL SUL- FQNATES F IMPRGVED OIL SOLUBILITY Earl Amott, Berkeley, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application September 4, 1943, Serial No. 501,339

This invention relates to the purification of sulfonated compounds by means of normally gaseous solvents such as propane, and more particularly to the oil solubility of propane extracted sulfonates.

In the refining of hydrocarbon oils with concentrated or fuming sulfuric acid a sulfonic compound is produced. This sulfonic compound is comprised of hydrocarbon oil and sulfonic acids, the sulfonic acids are of tWo types, the pref erentially water-soluble sulfonic acids which have been designated in the art as green acids and the oil-soluble sulfonic acids which are called the mahogany acids. The sulfonic compound above mentioned containing hydrocarbon oil and sulfonic acids is then neutralized with basic substance, such as calcium hydroxide, calcium carbonate, sodium hydroxide, lime slurry, etc., thereby forming sulfonates in hydrocarbon oil. In order to facilitate a subsequent settling step, if so desired, a diluent, such as petroleum naphtha, liqud propane, liquid butane or the like may be added. This addition may take place, at the discretion of the operator, prior or subsequent to the above mentioned neutralization step.

The resulting product of neutralization comprising an unsulfonated oil, sulfonates, solids, Water and diluent is then settled, centrifuged or filtered, resulting in a hydrocarbon layer containing unsulfonated oil, sulfonates, suspended solids and dissolved water and an aqueous layer containing solids and free water. The hydrocarbon layer is removed and then subjected to fractional distillationthereby removing a part of the diluent and the dissolved water leaving a hydrocarbon fraction comprising unsulfonated oil, sulfonates, suspended solids and diluent. The hydrocarbon fraction is again settled resulting in the removal of the suspended solids. The remaining hydrocarbon fraction is then subjected to a second fractional distillation, which removes the hydrocarbon diluent leaving a metal sulfonate concentrate comprising unsulfonated oil and sulfonates.

The metal sulfonate concentrate is then treated with a light hydrocarbon such as propane, this mixture is thoroughly agitated and heated to a temperature which in the case of propane treatment, as distinguished from other light hydrocarbon treatment, is between about 120 to 204 F. The resulting mixture is then allowed to settle resulting in a substantially soap-free oil fraction and a relatively pure soap fraction, consisting of both the mahogany and green soaps.

In the refining of viscous mineral oils for the 7 Claims. (Cl. 252363.5)

production of medicinal oil or white oil only the mahogany soaps are recovered while the green acids are removed with the resulting sludge created during the sulfonation process. The neutralized metal sulfonate concentrate, containing only the mahogany soaps as distinguished from the green soaps is then treated with a light hydrocarbon, such as propane, at a temperature which in the case of propane, is between about to 204 F., resulting in a substantially soapfree oil fraction and a relatively pure soap fraction, comprising oil-soluble mahogany soaps. The fact that these mahogany soaps are highly soluble in oil, makes it a relatively simple matter to redissolve the relatively pure soap fraction in a carrying vehicle such as naphtha, parent oil or a foreign lubricating oil.

In the production of sulfonates comprising both the oil soluble mahogany soaps and the water soluble ,green soaps, an added problem arises after the propane extraction treatment and the subsequent separation of the relatively pure soap fraction from the substantially soap-free oil fraction. The problem mentioned above is that of creating a solution comprising the relatively pure soap fraction in a Vehicle of oil. Experience has shown that relatively pure soap fractions consisting of both water soluble green soaps and oil soluble mahogany soaps are not readily soluble in oil.

The object of this invention is to treat said metal sulfonate concentrate in such a manner that the resulting pure soap fraction will thereby become more readily soluble in the desired oil vehicle.

In order to overcome the relatively low rate of solubility or insolubility of the relatively pure soap fraction mentioned above, I have found that by properly controlling the amount of oil incorporated within the relatively pure soaps of the type above described, any desired ease of solubility of the soap in naphtha or in oil may be realized, in other words, soaps associated with relatively small amount of oil will dissolve in naphtha or in oil with an ease in proportion to the amounts of oil therein contained.

In the practice of my invention the following procedure is followed: The calcium sulfonate concentrate containing natural oil and sulfonates of both the green and mahogany acids is completely clarified by filtration with a filter aid such as Super-eel. Therefore, in the practice of my invention, I use a solid free calcium sulfonate concentrate, This concentrate is introduced into either av multi-stage batch propane extraction unit or a continuous counter-current extraction unit equipped with any suitable agitating means. A relatively small quantity of propane-insoluble high molecular weight oil is introduced into the above mentioned extraction unit along with the solid-free calcium sulfonate concentrate. The above mentioned propane-insoluble high molecular weight oil includes any desirable oil-soluble polymer, resin or residuum substantially insoluble in liquid propane at about 190 F. and preferably of low melting point. This includes wax olefin polymers, poly-isobutene polymers, poly-propene polymers and the like obtained by polymerization of high and low molecular weight unsaturates and may include alkylation accompanied by polymerization. Heavy residual oils and naturally occurring or synthetic asphalts, which are propane insoluble may also be employed. The propane insoluble portion of ordinary Edeleanu extract (produced by extracting lubricating oil with liquid sulphur dioxide) may also be used. These are all oil soluble high molecular weight hydrocarbon materials which are substantitally insoluble in liquid propane at 190 F.

The above mentioned types of propane insoluble high molecular weight oil is of a type that is readily rejected by propane. It is known and is shown in U. S. Patent 2,059,838 that under certain conditions propane dissolves oil and at the same time rejects sulfonate soaps, thus permitting a fractionation. It is one of the objects of this invention to recover the greatest yield of soaps possible, and as a prerequisite to this object complete separation of soap from the natural oil must be obtained inasmuch as any soap remaining in the oil phase probably represents a loss. One of the most important factors in determining the yield of oil-free soaps is the amount of ejecting medium used, that is propane. As a result of my research, I have found that with the increased amounts of propane used corresponding increases of soap yields are obtained. A designated volume of propane is then introduced into the mixture of calcium sulfonate concentrate and propane-insoluble high molecular weight oil.

Another important factor in determining the yield of oil-tree soaps is the temperature at which the extraction is carried out. As a general rule the higher the temperature, the better is the corresponding yield of soap. The limiting temperature is of course the critical temperature of propane (204 F.) at which all of the oil as well as the soap is rejected. The ideal temperatures have been found to be in the case of propane 120 to 204 F. The above mixture consisting of calcium sulfonate concentrate, propane-insoluble high molecular weight oil" and propane is thorougl'ly agitated while the temperature is gradually increased up to the desired range, that is above about 120 F. and below about 204 F. The resulting product is allowed to settle for a designated period of time, wherein the propane-insoluble high molecular weight oil coated soap is settled out, leaving an upper layer consisting of propane and oil. The propane-oil layer is removed leaving a dry, brittle, easily-powdered polymer coated soap capable of being handled or shipped in paper bags or any other des red container. The removed oil fraction contains less than about 3% of soap, and the soap fraction is some four times as concentrated as the original concentrate. This soap is readily solubl in either naphtha, displaced native oil or some other selected oil stock.

This invention will also apply to the preparation of soaps of sulfonic acids other than the calcium soaps, especially those of the other alkaline earth metals, such as strontium and barium, although it also applies to the preparation of sulfonates of other metals of group II such as magnesium and zinc, and other polyvalent metals such as aluminum, iron and the like, as Well as metals of roup I such as the alkali metals, sodium and potassium, as well as copper and silver and the like.

This invention is applicable also to preparation of metal salts by any method wherein the above mentioned metal soaps are prepared from mixtures containing sulfonic acids, especially where the sulfonic acids are in the presence of hydrocarbons which were present during the sulfonation.

As a specific example of the application of this invention, I used as stock a calcium sulfonate concentrate, containing both the green and mahogany soaps, having a 3.8 sulfate ash value with a soap content of 22%. The above mentioned calcium sulfonate concentrate was prepared from S. A. E. 40 lubricating oil from naphthenic California crude with a viscosity index of 36, a viscosity gravity constant of 0.853 and a pour point of -15. In the preparation of the above named concentrate, I used about to grams of S. A. E. 40 lubricating oil from naphthenic California crude as stated above. This lubricating stock was sulfonated with fuming sulfuric acid (30% $03 by weight) employing a ratio of 34 grams of acid per 100 grams of oil, and thoroughly agitating at room temperature for a period of 15 minutes. The resulting product Was then neutralized by the addition of a slurry of lime. Following the neutralization step a diluent Was added, that is naphtha (ZOO-300 F. boiling point) in the amount or 100 volume percent of the lubrieating oil stock charge. The resulting product was allowed to settle. During this settling step the bulk of the solids and nearly all the free water stratified as a lower aqueous layer which was drawn oil, leaving a hydrocarbon layer consisting essentially of naphtha, oil, sulfonates and a small amount of water in solution. This h drocarbon layer also contained an appreciable amount of suspended solids, these solids were removed by further settling and filtration through Super-eel. The clarified product was then subjected to a distillation treatment whereby the naphtha and dissolved water were removed leaving a pure calcium sulfonate concentrate as mentioned above.

This clarified sulfonate concentrate was split up into two separate samples. The first sample was placed in a jacketed steel bomb which acted as the extraction vessel. Twelve volumes of propane was introduced into the bomb. While agitating this mixture thoroughly, I gradually increased the temperature of the mass to about F. The resulting product was allowed to settle for about 30 minutes wherein the soap was settled out, leaving an upper layer consisting of propane and oil. The propane-oil layer was removed leaving a dry, brittle solid soap remaining which had a sulfate ash value of approximately 15.0%. The oil fraction had a sulfate ash value of about 0.027%. The above mentioned soap fraction was found to be soluble in naphtha dissolving fairly readily to give an absolutely bright and clear solution. The same material, how ever, dissolved in the native oil and other oils such as a typical solvent refined paraffinic oil or other suitable lubricant with considerable difficulty. As

a specific example, the above mentioned soap fraction was introduced into a California solvent refined parafiinic oil, having a viscosity index of 90, viscosity gravity constant of .810 and a pour point of 5. The above mentioned mixture was heated to 300 F. and after a period of sixty minutes, of the soap fraction remained undissolved.

The second sample was placed in a jacketed steel bomb identical with the one mentioned in the preparation or the first sample, to this was added 3% of wax olefin polymers having a viscosity index of and a pour point of 55, followed by 12 volumes of propane. This mixture was then thoroughly agitated, while the temperature was gradually raised to F. The resulting product was allowed to settle for about 30 minutes wherein the poylmer coated soap settled to the bottom of the bomb, leaving an upper layer consisting of propane and oil. The propane-oil layer was removed leaving a dry, brittle polymer coated soap remaining which had a sulfate ash value of approximately 13.5. The oil fraction had a sulfate ash value of about 0.027%. The above-mentioned polymer coated soap fraction was found to be readily soluble in naphtha, native oil and other oils such as typical solvent refined paraflinic oil or other suitable lubricant. As a specific example, the above mentioned polymer coated soap fraction was introduced into a California solvent refined parafliinic oil, having a viscosity index of 90, a viscosity gravity constant of .810 and a pour point of 5. The above mentioned mixture was heated to 300 F. After a period of five minutes all of the soap lraction had dissolved.

While I have described the use of propane as an extraction medium, it should be understood that ethane, isobutane, butane, and similar normally gaseous treating agents may be used in the place of, or in admixture with, propane, the treating temperatures being lowered with the lighter extraction medium and increased with the heavier ones.

The foregoing exemplary description of my invention is not to be considered as limiting since many variations may be made within the scope ing mixture and heating it to a temperature be tween about 120 F. and about 204 F., in the presence of a liquefied normally gaseous hydrocarbon, whereby two phases are formed, one a liquid phase comprising substantially sulfonate-free oil dissolved in said normally gaseous hydrocarbon and the other a solid phase comprising the desired dry sulfonates containing said high molecular weight hydrocarbon material, settling and separating said phases.

2. A method according to claim 1 in which the high molecular weight hydrocarbon material is an oil.

3. A method of producing dry metal sulfonates of improved oil solubility from an oil solution of said sulfonates, which comprises adding to said solution an oil soluble asphalt which is substantially insoluble in liquid propane at about F., in a small proportion sufiicient to improve substantially the oil solubility of said metal sulfonates, agitating said mixture and heating it to a temperature between about 120 F. and about 204 F. in the presence of sufiicient liquid propane to cause the product to separate into two phases, one a liquid phase comprising substantially sulfonate-free oil dissolved in propane and the other a solid phase comprising the desired dry sulfonates containing said oil soluble asphalt, and settling and separating said phases.

4. A method of producing dry metal sulfonates of improved oil solubility from an oil solution of said sulfonates which comprises adding to said solution an oil soluble high molecular weight olefin polymer which is substantially insoluble in liquid propane at about 190 F. in a small proportion sufficient to improve substantially the oil solubility of said sulfonates, agitating the resulting mixture and heating it to a temperature between about 120 F. and about 204 F. in the presence of a sufficient amount of liquid propane to cause the formation of two phases, one a liquid phase coinprising a substantially sulfonate-free oil dissolved in propane and the other a solid phase comprising the desired dry sulfonate containing said high molecular Weight olefin polymers, settling and separating said phases.

5. A method according to claim 4 in which the olefin polymers comprises an isobutene polymer.

6. A method according to claim 1 in which about 3% of the high molecular weight hydrocarbon material is employed.

7. A method according to claim 1 in which the high molecular weight hydrocarbonmaterial is an Edeleanu extract.

EARL AMOTT. 

